AbstractBased on regional flora and a Digital Elevation Model (DEM), we investigated altitudinal patterns of seed plant richness in Lijiang, Yunnan. The results indicated that species richness, species density, available area, and the species richness predicted by the mid-domain effect increased first and then decreased after reaching their maximum, showing a unimodal pattern against elevation. There was strong correlation between species richness, available area and mid-domain effect. The area was a much more important factor, explaining 80.2% of the pattern of species richness, whereas the influence of the mid-domain effect was relatively weak, explaining only 11.3%.